Feb. 28, 2012: T.J. Lane, a suspect in Monday's shooting of five students at Chardon High School is taken into juvenile court by Geauga County deputies in Chardon, Ohio.
(AP)

The left image, provided by family, shows Daniel Parmertor, who died Monday following a shooting rampage at Chardon High School in Ohio. Russell King Jr., right, shown in a yearbook photo, was declared dead on Tuesday, authorities said.

The teenage suspect in a deadly shooting rampage at an Ohio high school chose his victims randomly, authorities said Tuesday, as prosecutors prepare to file charges and are expected to ask to try the boy as an adult.

Judge Timothy Grendell set a Thursday deadline for prosecutors to file charges and ordered the suspect, 17-year-old T.J. Lane, to remain in custody at least through the followup hearings.

Lane is suspected of killing three and wounding two in the shooting Tuesday at Chardon High School. Prosecutor David Joyce said Lane admitted that he brought the gun and a knife to school and fired off shots but picked his victims "randomly."

Authorities say they will be looking for indicators as to what prompted Lane to fire 10 rounds at a group in a cafeteria, though bullying and drugs were not being looked at as likely motives.

"He chose his victims at random," Joyce said. "This is not about bullying. This is not about drugs. This is someone who's not well, and I'm sure in our court case we'll prove that to all of your desires and we'll make sure justice is done here in this county."

Joyce would not elaborate, and prosecutors and defense attorneys are under a gag order imposed by Judge Grendell at Joyce's request.

A lawyer for the suspect's family earlier had identified Lane to a Cleveland TV station as a high school junior who had been seen as an outcast by fellow classmates.

Russell King Jr., 17, Daniel Parmertor, 16, and Demetrius Hewlin, 16, were killed in the shooting.

Hewlin attended Chardon High School, but Kin and Parmertor were students at the Auburn Career Center, a vocational school, and were waiting in the cafeteria for their daily bus. Lane attended Lake Academy, a school for students with academic or behavioral problems. Authorities would not reveal why he was enrolled there.

Witnesses say the gunman opened fire on the group before being chased from the building by a teacher and apprehended by authorities about a half a mile away.

Witness Nate Mueller, whose ear was grazed by a bullet and was sitting at the table with other victims, told The Plain Dealer that King had recently started dating Lane's ex-girlfriend.

He "was silent the whole time," Mueller said. "That's what made it so random."

"My focus continues to be trying to help those so severely affected by this tragedy," Joseph Bergant, superintendent of Chardon Local Schools said in a press conference. "We're not just any old place, Chardon. This is every place. As you've seen in the past, this can happen anywhere, proof of what we had yesterday."

Chardon schools will open Thursday for parents and students to reintegrate students back into their programs, and schools are expected to return to a regular schedule on Friday.